First stars' light seen through extragalactic fog

SHINING like beacons through the gloom, blazar galaxies are helping to probe the diffuse glow of starlight that permeates the universe. This means we can take a peek at the very first stars, which are too distant to see directly.

It is not easy to measure the intensity of the fog of photons that makes up the extragalactic background because it is drowned out by the glare of our galaxy.

Using NASA's Fermi Gamma-ray Space Telescope, Anita Reimer of the University of Innsbruck in Austria and colleagues looked for gamma rays coming from distant blazars, which dim as they interact with the photon fog (Science, doi.org/jn5).

Using data on how bright the blazars should be and how far away they are, the team could work out the amount of dimming and thus the intensity of the fog. Subtracting data on known stars leaves only the first stars' light.

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.